This invention in general relates to fiber optics and in particular to connectors for demountably coupling pairs of optical fibers or the like.
Communication by means of optical electromagnetic radiation transmitted along optical fibers is a well-established practice made possible over the past 25 years by developments in a number of areas including sources, detectors, and low-loss transmission fiber.
Compared with other medium of like size, a major advantage to optical fiber as a communications medium resides in its much higher capacity to transfer information. This comes about because a communication channel requires the same bandwidth wherever it operates in the spectrum, and the higher frequency optical regions where fibers operate inherently have higher channel and thus information carrying capacity. This major advantage, however, is also a major disadvantage when it comes to making connections between already small fibers because the consequences of signal loss are proportionately more severe.
To solve the coupling problem with minimal signal loss, those skilled in the art have taken two basic approaches to the design of connectors, devices by which fibers or other fiber optic elements can be optically coupled and decoupled with reasonable frequency.
The first basic approach involves the use of the precision butt joint. Here, practically achievable physical structures are employed to meet the axial, lateral, and azimuthal precision required for proper alignment with minimum loss. Usually, this approach reduces to the use of a ruggedized connector in which the fibers themselves are fixed in precision ferrules which thereafter are aligned to complete the ultimate positioning of the fibers with respect to one another.
The second basic approach involves the use of lenses to provide enlarged images of the fibers which then are physically aligned. The strategy here is to trade off the strict linear dimensional requirements involved with the butt joint approach against a more exact angular tolerance. Typically, the lens connector utilizes two symmetrically arranged lenses structured so that fibers placed at the focii are imaged one onto the other. The geometry which is of major importance using this approach is usually integrated into the optical structure, and the tolerances of importance relate to lens tilt, beam aiming, and the accuracy with which the fibers are located with respect to the focus of their respective lenses. As an example of this type of a connector, reference may be had to U.S. Pat. No. 4,421,383 issued to W. John Carlsen on Dec. 20, 1983 and entitled "Optical Fiber Connectors".
Although lens connectors are known in the art, it is a primary object of the present invention to provide improved lens connectors for coupling pairs of optical fibers or other fiber optic elements.
It is another object of the present invention to provide a lens connector which is easier to manufacture than previous connectors of this type.
It is yet another object of the present invention to provide a lens connector for coupling pairs of fibers or other elements having different numerical apertures.
Other objects of the invention will, in part, be obvious and will, in part, appear hereinafter. The invention accordingly comprises the structure exemplified in the detailed disclosure which is to follow.